调整Data Guard保护模式

1.查看主库当前保护模式

SQL>selectprotection_mode,protection_level from v$database;

PROTECTION_MODE                   PROTECTION_LEVEL

------------------------------                    -------------------------------

MAXIMUMPERFORMANCE          MAXIMUM PERFORMANCE

2.修改主库dest参数

SQL>alter system set log_archive_dest_2='SERVICE=standby OPTIONAL LGWR SYNC AFFIRM VALID_FOR=(ONLINE_LOGFILES,PRIMARY_ROLE)  DB_UNIQUE_NAME=orcl2';

System altered.

3.修改主库保护模式

SQL>alter database set standby database to maximize availability;

Database altered

附：下面列出不同数据保护模式的修改方法

SQL > alter databaseset standby database to maximize protection;   

SQL > alter databaseset standby database to maximize availability; 

SQL > alter databaseset standby database to maximize performance; 

4.重启主库

SQL>shutdownimmediate;

SQL>startup;

5.查看主库保护模式

SQL>selectprotection_mode,protection_level from v$database;

PROTECTION_MODE      PROTECTION_LEVEL

----------------------------        ------------------------------

MAXIMUMAVAILABILITY   MAXIMUM AVAILABILITY

此时可以看到备库告警日志内输出以下内容：

Primary database is in MAXIMUM AVAILABILITY mode

Changing standby controlfile to MAXIMUM AVAILABILITY level

6.修改备库的dest参数

SQL>alter system set log_archive_dest_2='SERVICE=primary OPTIONAL  LGWR  SYNC  AFFIRM  VALID_FOR=(ONLINE_LOGFILES,PRIMARY_ROLE)  DB_UNIQUE_NAME=orcl1';

System altered.

7.查看备库数据保护模式

SQL>select protection_mode,protection_level from v$database;

PROTECTION_MODE      PROTECTION_LEVEL

----------------------------------------

MAXIMUMAVAILABILITY MAXIMUM AVAILABILITY

8.验证最高可用性模式

1).备库关闭后主库的状态（主库的PROTECTION_LEVEL标示为RESYNCHRONIZATION状态）：

SQL>select protection_mode,protection_level from v$database;

PROTECTION_MODE      PROTECTION_LEVEL

------------------------------     -----------------------------

MAXIMUMAVAILABILITY   RESYNCHRONIZATION

2).备库恢复数据恢复后，主库的状态：

SQL>select protection_mode,protection_level from v$database;

PROTECTION_MODE      PROTECTION_LEVEL

-----------------------------      --------------------------------

MAXIMUMAVAILABILITY   MAXIMUM AVAILABILITY